A point of sale (“POS”) device can include various components, such as a processor, a card reader, a network connection interface, and a receipt printer. Card readers are typically built to read transaction information from cards, such as credit cards or debit cards.
Printers allow text and other visual content to be printed onto paper via transfer of liquid ink, of solid toner, or thermal modification of paper. Printers typically include various moving parts and/or other high-energy components, such as lasers or thermal print heads. As such, printers are some of the most energy-hungry devices typically used in personal computing.
Portable devices are often powered by rechargeable or replaceable batteries with limits on their power discharge capability rates. That is, batteries are typically only able to discharge up to a certain amount of current, power, or voltage. When a battery or other power source is unable to supply enough power to the components it is connected to, this can cause various issues. These issues can include undervoltage, a situation where average voltage of powered components drops below intended or demanded levels, sometimes referred to as a brown-out. Undervoltages, or brownouts, can often result in powered components unable to perform the actions they are tasked with, and can sometimes result in permanent damage to the powered components. While large industrial machinery and municipal power grids can, in some cases, siphon energy from backup power sources when necessary, portable devices are typically limited to their respective batteries. POS devices facing brownouts can cause financial issues such as failed payments or double payments or security issues related to storage of sensitive data.
Low temperatures exacerbate situations where brownouts may already be a risk. Batteries are typically capable of outputting energy at higher rates when they are at higher temperatures, and are only capable of outputting energy at lower rates when they are at lower temperatures. At −20 degrees Celsius (−4 degrees Fahrenheit), most batteries stop functioning entirely. Some batteries can even suffer permanent damage at low temperatures, sometimes by developing permanent short circuits or by frozen electrolytes such as lead acid cracking battery enclosures. Likewise, printers often fail to function properly at lower temperatures, either due to an increase in ink viscosity, a decrease in laser/toner fusion efficacy, or a decrease in thermal print head efficacy. Printers include many moving parts, causing printers to often become fragile at lower temperatures as well.
Thus, there is a need in the art for improved power management and undervoltage protection in portable point of sale (POS) devices, particularly at low temperatures.